The development of electronic technologies has promoted the development of telecommunication using an electromagnetic wave as a medium, and telecommunication has expanded and is being used as various types of wireless communications of the day. Basically, wireless communication modulates information to be transmitted to a radio wave and transmits the radio wave through a power amplifier (PA), so that the received radio wave is demodulated at the side of a receiver to obtain the information.
To improve the efficiency of wireless communication, researchers introduced a concept of time division that configures different message channels for each time slot in a non-overlapping manner of the message channels by temporally separating the respective messages, to allow parallel transmission over a single transmission medium. Using this time division, a pulse of one communication path can be inserted using a rest period between pulses on another communication path, thereby allowing temporally different multiple communications. Particularly, in the time division transmission scheme, a scheme that enables bidirectional communications using one frequency by dividing one frame into a transmission part and a reception part is referred to as time division duplex (TDD). Generally, wireless communication uses different frequencies for transmission and reception, while a TDD scheme is characterized in that a single frequency is temporally divided for separate use of transmission and reception, thereby allowing bidirectional communications.
Meanwhile, a TDD-based wireless communication system and a remote node (or a wireless communication terminal) for use therein receive a signal from a host node and transmit its own signal to the host node. With the functional diversity and structural complexity of the remote node, in turn, a difficulty in power management occurred to the remote node. Particularly, with the advanced function of the remote node, various studies have been proposed to save the power consumed by the remote node making a mutual communication with the host node. The non-patent literature as stated below indicates a situation in which excessive power is consumed in reverse channel transmission from a remote node to a host node.
(Non-patent Literature 1) Hichan Moon, Suhan Choi, “Channel adaptive random access for TDD-based wireless systems”, IEEE Trans. Vehicular Tech., pp. 2730-2741, July 2011.